In the current state of the art of LED dimmer technology, one of the ways to control multiple banks of LEDs is the use of a series dimmer control. For purposes of the invention a “bank” is defined as a series connection of one or more LEDs. This control works by turning on the LEDs during only a portion of the time at the beginning or end of the positive and negative input sine wave of the AC power source. The control involves various types of semiconductors to implement this switching, but when multiple banks are dimmed, all of the banks dim together, at the same time.
An alternate way of dimming multiple LED banks is to use a Pulse Width Modulated (PWM) control signal going to the driver circuitry. Typically, in the industry, a zero to ten volt pulse signal is applied to the dimming switching device. The wider the pulse that controls the switching device to conduct current to the LED banks, the brighter the LED banks appear. All LED banks behave in unison.
In the first mentioned approach, utilizing a series dimmer circuit, there is the problem of noticeable brightness and visible lamp flicker, especially when there is a dimmer setting for very dim lighting. In addition, if there is minor perturbation of the voltage level, there is a very discernible short term brightening or dimming of the LEDs. This happens to all of the banks simultaneously, since the dimmer circuitry's control setting affects all of the banks at the same time.